Glycogen Storage Disease Type II

The Pompe Registry is a global, multicenter, international, longitudinal, observational, and voluntary program for patients with Pompe disease, designed to track the disease's natural history and outcomes in patients, both treated and not. Data from the Registry are also used to fulfill various global regulatory commitments, to support product development/reimbursement, and for other research and non-research related purposes. The objectives of the Registry are: * To enhance understanding of the variability, progression, identification, and natural history of Pompe disease, with the ultimate goal of better guiding and assessing therapeutic intervention. * To assist the Pompe medical community with the development of recommendations for monitoring patients, and to provide reports on patient outcomes, to optimize patient care. * To characterize the Pompe disease population. * To evaluate the long-term effectiveness of alglucosidase alfa.

This is a single group, 52-week treatment, Phase 4, open-label, single-arm study to assess the safety and efficacy of avalglucosidase alfa IV infusion in male and female Chinese participants with IOPD who are treatment-naïve or were previously treated with ERT. Study details include: * The study duration: total study duration is approximately 64 weeks. * Screening period of up to 8 weeks * Treatment period of 52 weeks * Follow-up period of 4 weeks. (if the participant enrolls in another study or receives commercially available ERT, the follow-up period may be reduced from 4 to 2 weeks) * The number of visits will be 30, including 29 site visits and 1 phone call follow-up visit.

The aim of this study is to assess if dosing frequency reduction of alglucosidase alfa 20 mg/kg once every 2 weeks to once every 4 weeks is safe and does not lead to increased progression of disease in a selected group of patients with late-onset Pompe disease.

This study is aimed to investigate that whether the higher dose ERT improve safety and clinical outcomes of Pompe disease patients. Also, wish to develop a new therapeutic recommendation and hope that it could improve the long-term outcomes of Pompe diesease patients.